A conventional pen for painting, such as a correction pen, comprises generally a round nib to be catched at the front end of a tube. The slim gap between the nib and the tube is used for discharging the liquid, so the discharging quantity is limited. Furthermore, since the contact between the pen nib and the paper is just a point, it has to smear back and forth with the pen for correction. Sometimes the thickness of the liquid remained on the paper is not uniform, so the paper can not be fed into a facsimile machine or the liqiuid residues are rubbed to be remained in the machine to cause problems.